Devices using millimeter-wave band frequencies are expected to be applied to a backbone line device between radio base stations due to broadband nature and applied to a sensing device such as a radar due to sharp rectilinearity. Recent millimeter wave semiconductor devices are supplied to the market in the form of a surface-mount terminal such as a ball grid array in a state where a transmission circuit or a reception circuit, or both the functions are integrated in one package. Accordingly, products using these devices are premised on the use of a component mounter and a reflow furnace, and a low-cost assembly is also realized in products intended for a millimeter-wave band.
A millimeter wave semiconductor device used in a millimeter wave radar is a device with a wide signal dynamic range and high sensitivity. Factors of a malfunction of the semiconductor device include interference of unnecessary radio waves from the outside and a shield case using a metallic cover is used as a measure for suppressing unnecessary radio waves as disclosed in PTLs 1 to 4.